Stress-Strain State of the Lithosphere of the Kamchatka Pacific Coast Before the July 29, 2025 Earthquake

On July 29, 2025, an earthquake with a moment magnitude of MW 8.8 occurred off the coast of Kamchatka, becoming the strongest in the Kamchatka seismofocal zone since 1952. With the aim of reconstructing the parameters of the modern stress field of the Earth’s crust on the Pacific coast of Kamchatka prior to this event, a new modification of the cataclastic analysis method of discontinuous displacements was applied. Stress determination was performed based on earthquake focal mechanism data. The calculations of the stress tensor components were carried out within domains identified as quasi-homogeneous in their deformation state. Each such domain corresponded to its own homogeneous dataset of earthquakes. The results of the stress reconstruction obtained in the study region revealed characteristic features of the spatiotemporal distribution of the stress state parameters. Based on the analysis of the stress state, seismotectonic domains with different deformation regimes were identified. A significant feature of the stress field is associated with the junction area of the Aleutian and Kamchatka seismofocal zones, where the main heterogeneities of the stress field are observed.